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[Display omitted] • The Gejiu mafic-intermediate intrusions formed during 84.6–82.1 Ma, consistent with ore-forming granites. • Mafic-intermediate intrusions resulted from AFC processes of partial melts of enriched lithospheric mantle. • Mixing between crustal Sn-rich granitic magma and Cu-rich mafic-intermediate magma formed giant Sn-Cu deposit. • Late Cretaceous southwestern slab roll-back of the Neo-Tethyan Ocean controlled formation of giant Sn-Cu deposit. The giant Gejiu ore field, located in the southeastern Yunnan Province, China, developed a large-scale Sn–Cu mineralization related to the Cretaceous felsic–mafic magmatism. However, the genesis of Cretaceous mafic–intermediate intrusions remains controversial, which limits our understanding of the Cu source, Sn–Cu symbiotic mechanism, and geodynamic setting of the Gejiu region. To elucidate these issues, we conducted geochronological and geochemical evaluations on the Gejiu mafic–intermediate intrusions, including gabbro, syenite, and monzonite. The mafic–intermediate intrusions formed in 82.1–83.8 Ma, which are contemporaneous with ore-forming granites and ore bodies within the error range. Combined with the cumulus texture in gabbro, linear or parallel elemental plots, and similar and enriched Sr–Nd–Hf isotopes ((87Sr/86Sr) I = 0.708870–0.709811; ε Nd (t) = − 5.24–−7.70; ε Hf (t) = − 4.8–2.5), the gradually increased Sr isotopes from gabbro through syenite to monzonite indicated that the Gejiu mafic–intermediate intrusions were formed by fractional crystallization and varying degrees of crustal assimilation of partial melts of an enriched lithospheric mantle. Based on the above research, we compiled geochronological and geochemical data of magmatic–metallogenic events in the region. The Sr–Nd isotopic and elemental ratios (i.e., Zr/Hf, Nb/Ta, Rb/Sr and Ba/Rb) of the Gejiu granites are located between the mafic–intermediate intrusions and spatially temporally connected Laojunshan granites, which indicate that the magma mixing between the enriched mantle–derived Cu-rich magma and metasedimentary rock–derived Sn-rich granitic magma generated Sn–Cu-rich granitic magma. This magma then evolved into the giant Gejiu Sn–Cu deposit via crystal fractionation and fluid exsolution. Combined with the regional geological data and spatiotemporal framework of Sn–polymetallic deposits, the magmatic–metallogenic model of the giant Gejiu Sn–Cu ore field further demonstrates that the southwestern slab rollback of the Neo-Tethyan oceanic plate during the Late Cretaceous controlled its formation. [ABSTRACT FROM AUTHOR]

Pterosaurs are powered flight vertebrates that first emerged in the Late Triassic and persisted until the end of the Cretaceous. Recent studies on the ecological niches and habitats of pterosaurs, based on discoveries of Cretaceous bone beds in China, Brazil, Morocco, and other locations, suggest a decline in pterosaur diversity during the mid-Cretaceous. Various hypotheses have been proposed to interpret this phenomenon. This study focuses on newly discovered pterosaur tracks at the Upper Cretaceous (Truonian) Hwasun Seoyuri tracksite in Korea. The analysis is based on pterosaur tracks from in situ and ex situ specimens that originate from a variety of stratigraphic levels. The evidence found suggests that the Hwasun Seoyuri tracksite was occupied by small pterosaurs over an extended period, with indications of recurrent activity across at least six levels. Furthermore, the footprint sizes observed across these multiple layers follow a non-skewed normal distribution. Considering the known logarithmic growth characteristics of pterosaurs, this result suggests a predominantly immature population at this site. The prevalence of mid-Cretaceous non-marine pterosaur tracksites on the Korean Peninsula may reflect broader ecological shifts for pterosaurs during this period. This evidence is considered alongside the habitat shifts suggested by other non-marine pterosaur fossil sites in China and Brazil, as well as with indications of the decline in Late Cretaceous non-marine basins. • New pterosaur tracks were found in the Late Cretaceous of Hwasun Seoyuri in Korea. • The trackmaker may be young or small azhdarchid or unknown taxa. • The track size distribution suggests immature pterosaur gregariousness. • The decrease in late Cretaceous pterosaurs could be linked to habitat shift. [ABSTRACT FROM AUTHOR]

Caenagnathid oviraptorosaurian dinosaurs, long considered enigmas, have now become relatively easy to recognize in the fossil record of Asia and North America. This has revealed their presence in several formations spanning the Late Cretaceous, providing new insights including showing that they were more widespread in the southern parts of North America than previously recognized. Here we add to this record by describing a nearly complete right tibia from the upper Campanian De-na-zin Member of the Kirtland Formation of New Mexico, which represents the first caenagnathid material from these beds. The bone is nearly identical in morphology and size to its counterpart in the Mongolian Elmisaurus rarus , reinforcing a suite of previously-identified features that allow for straightforward recognition of caenagnathid tibiae. The growing body of caenagnathid material continues to blur boundaries between features once considered distinct, raising doubts that some taxa established from sparse material, including Ojoraptorsaurus boerei , are actually valid. [ABSTRACT FROM AUTHOR]

The Cenomanian (lowermost Upper Cretaceous) faunal assemblages are of high interest in understanding the turnovers that took place between the Early and the Late Cretaceous, resulting in significant differences. In this context, the analysis of the association of reptiles found in the Algora fossil site (Guadalajara Province, Central Spain) is of great interest since it represents the first European Cenomanian site with a high concentration of macrovertebrate remains. A new pythonomorph ‘lizard’ from Algora, Carentonosaurus algorensis sp. nov., is described here. It is the second representative of this European genus. Its microanatomical study reveals that an extreme pachyosteosclerosis affected at least its dorsal vertebrae, suggesting adaptations for slow-swimming habits in shallow-water environments. Consequently, this new taxon is interpreted as a slow swimmer, hovering near the bottom of near-shore marine environments of the Late Cretaceous European Archipelago and, more specifically, along the shores of the larger Iberian Island for that period. This is in concordance with the high diversification of ‘pachyostotic’ pythonomorphs recorded during the Cenomanian, allowing the subsequent adaptation of this lineage to open marine environments.

A theropod femur from the Late Cretaceous Kansai locality in Tajikistan (Yalovach Formation, Santonian) is referred to the family Therizinosauridae based on a combination of the following derived characters: the bone is straight in the anteroposterior plane; the femoral head is directed dorsomedially; the femoral neck is constricted between the femoral head and the great trochanter; the great trochanter and the femoral head are separated by a depression; the anterior trochanter is reduced, cylindrical; the ventral margin of the femoral head does not project beyond the margin of the femoral neck. The Kansai therizinosaur is most similar in the structure of the femur with unnamed therizinosaurs from the Turonian of Uzbekistan and the Santonian–Campanian of Western Kazakhstan. [ABSTRACT FROM AUTHOR]

New umbellaoolithid and faveoloolithid eggs were discovered from the early Late Cretaceous deposit in the Xiuning Basin, Anhui Province, China, and the samples were examined for elemental and isotopic compositions to reconstruct the geochemical environment. The results show that the trace elements consist of Sr, Mn, Ti, Ba, As, La, Cr, Ni, Pb, Cu, Zn, Co and Ir. The abnormal Sr and Mn were deposited in the eggshell mainly through material exchange of dinosaurs, and the high Ir concentration of surrounding rocks in the Xiuning Basin is conformed to the early Late Cretaceous Ir anomaly. The δ13C compositions of eggshells suggest that the palaeovegetations are supposed to be −20.191‰ and −21.156‰ showing C3 plant and high CO2 concentration, as well as low mean annual precipitation. The δ18O compositions of eggshells indicate that the drinking water was mainly composed of meteoric water and plant leaf water, and the mean palaeotemperature was approximately 19°C. Based on the geochemical compositions of eggshells, the Ni content, the Sr/Ba ratio and the palaeoclimate index of surrounding rocks, the palaeoenvironment in the Xiuning Basin were dominated by alluvial fans and river systems with semi-arid climate in the early Late Cretaceous. [ABSTRACT FROM AUTHOR]

This paper documents the occurrence of Skolithos linearis, Planolites beverleyensis, and Thalassinoides isp. in the Cárdenas Formation (Late Cretaceous), southeastern San Luis Potosí, central Mexico. This is the second record of S. linearis for this lithological unit, while P. beverleyensis and Thalassinoides isp. are documented for the very first time in this formation. The ichnoassemblage is referred to the Cruziana Ichnofacies which, in concert with associated invertebrate body fossils (Exogyra costata), suggest a shoreface setting with moderate- to low-energy conditions and episodic storms. [ABSTRACT FROM AUTHOR]

In the previous paper, the geological ages of the Late Cretaceous, Paleocene, late Middle to Late Eocene, Oligocene and early Early Miocene were confirmed at the first time, based on the occurrences of both the age diagnostic larger foraminifera and associated planktonic foraminifera, from the Sashida limestone included basalt pebbles, Sashida, Kamo-Gun, south Izu Peninsula. Therefore, the Sashida limestone was made up of clastic carbonate rocks of various ages in essence as well as in outward form. In this paper; the age determination by the microfossil of larger and planktonic foraminifera was re-investigated by the Sr isotopic age determination from the same microfossil sample materials of the Sashida Limestone in order to get the age security As a result, the ages from 69.3 to 71.8 Ma (Late Cretaceous; Maastrichtian) and 2&8 to 33.3 Ma (Early Oligocene; Rupelian) were determined and supported the ages of foraminifera partial. While, analysis of chemical composition of the basalt pebbles was investigated in order to estimate the original generation tectonics. As a result, the basalt pebbles showed a unique composition of high magnesium and high alkali, similar to basalts of the lower Yugashima Group and were assigned to the alkali basalt series, which were thought to have emerged in the very early stage of the Shikoku Basin spreading. The antecedent of the Izu Peninsula was defined as the Izu landmass from the previous paper, which was inferred the lateral mobility toward east from the spreading, and the last, bordered on the north by the Honshu. [ABSTRACT FROM AUTHOR]

The late Cretaceous, Paleocene, late Middle to Late Eocene, Oligocene and early Early Miocene larger (benthonic) and planktonic foraminifera were confirmed for the first time, in addition to Early-Middle Miocene larger foraminifera, from the Sashida limestone included basalt pebbles beside the outcrop, which was covered by riverconstruction, and near there, Sashida, Kamo-Gun, south Izu Peninsula, Japan. The Sashida limestone consists of clastic carbonate rocks of various ages from the late Cretaceous through early Early Miocene to late Miocene or early Pliocene. From the research conclusion, the geology and geohistory of the Cretaceous-Paleogene Shimanto Group and Paleogene Setogawa Group along the Pacific Ocean as the pre-Yugashima Group, and the locus of lateral mobility of the Izu landmass of the antecedent of the Izu Peninsula were indicated as further research. [ABSTRACT FROM AUTHOR]

Surprisingly, after the Early Cretaceous taxonomic diversity recorded in Europe, which probably is largely an artifact of inadequate taxonomy and inflation of taxa, multituberculate mammals became extremely scarce in the Late Cretaceous in this continent, being reported exclusively from the uppermost Cretaceous continental deposits of the so-called "HaÈ›eg Island" in Transylvania, Romania. Such mammals have been documented from the HaÈ›eg and Rusca Montană sedimentary basins, as well as from the southwestern area of the Transylvanian Basin. All these records belong to the endemic family Kogaionidae. The present paper reports additional data related to the smallest Cretaceous kogaionid, Barbatodon oardaensis Codrea, Solomon, Venczel & Smith, 2014 based on a series of new isolated teeth recovered mainly from the type locality, Oarda de Jos (Oarda A). Furthermore, the fossil localities Oarda B and Vălioara are other new occurrences for the species. Based on this new material, the intraspecific variability of B. oardaensis is confirmed and its presence is attested in the three basins. Details related to the diversity of the "HaÈ›eg Island" kogaionids are also provided. [ABSTRACT FROM AUTHOR]

Abstract—A paleomagnetic study of the Okhotsk–Chukotka belt volcanics exposed in the region of the Kupol field (~66.9° N, 170.1° E) has been carried out. The studied rocks were formed between 85 and 95 Ma during the Cretaceous Normal Superchron (CNS). In most of the studied samples, the characteristic magnetization component is isolated. Its primary origin is supported by the positive fold test, magnetic mineralogy data, and similarity of the calculated paleomagnetic pole with that of coeval rocks from the same region. It is shown that the studied rocks were formed in high polar latitudes close to 80° N. The amplitude of paleosecular variation (PSV) of the geomagnetic field during CNS has been estimated. Depending on the calculation method, the estimates (and their confidence intervals) for ~81° N are Sb = 22.1° (19.5°; 24.7°) in case of using a fixed cut-off angle of 45° and Sb = 23.1° (20.3°; 25.7°) in case of the cut-off angle calculated by the Vandamme method. The obtained estimates generally support the existing models of PSV latitudinal dependence for CNS. At the same time, the estimates are less consistent with the model (McFadden et al., 1991) where PSV values are low at the equator and sharply increase with latitude than with the model (Biggin et al., 2008) predicting higher PSV values at the equator and their more gentle increase towards polar latitudes. Irrespective of the calculation method, the obtained estimates almost perfectly fit the PSV latitudinal dependences for the last 5 Ma. This means that the amplitude of secular geomagnetic variation during CNS, at least at high latitudes, was the same as it was during the last 5 Ma. The obtained result does not support the hypothesis that geodynamo regimes change at the transition from the periods of frequent geomagnetic reversals to superchrons (e.g., (Gallet and Pavlov, 2016)), which suggests, in particular, that the modern numerical models are not fully adequate to the real processes of generation of the geomagnetic field. [ABSTRACT FROM AUTHOR]

Dinosaur footprints occur in the Upper Cretaceous strata known as the Nubian Sandstone Formation in the south Eastern Desert, Egypt. The Nubian Sandstone unit is subdivided into three informal members: A lower member is marked by reddish‐brown, trough cross‐bedded, coarse‐ to medium‐grained sandstone interbedded with thin beds of varicolored mudstone, reflecting deposition in a braided fluvial system, a middle member is characterized by reddish‐white to yellow, planar cross‐bedded, medium‐grained sandstone with ferruginous siltstone intercalations, interpreted as meandering fluvial deposits, and an upper member consists of repeated coarsening‐upward cycles of rippled siltstone to fine‐ to medium‐grained sandstone and planar cross‐bedded, yellowish‐white sandstone, containing many vertebrate footprints and invertebrate trace fossils, reflecting deposition in a coastal to deltaic environment. Sixteen dinosaur footprints are recorded at the base of the upper member of the Nubian Sandstone, on inclined surfaces of rippled, fine‐grained sandstones. Twelve are overlapping each other and belong to distinct individuals of dinosaurs, the other four are distributed on a younger bedding surface. Twelve footprints are from more than one sauropod dinosaur, while three of the isolated footprints belong to a theropod dinosaur. The footprints described are semiplantigrade and digitigrade. This discovery is the second record of tetrapod footprints in Egypt and the first record of tetrapod footprints in the Eastern Desert. [ABSTRACT FROM AUTHOR]

[Display omitted] • ~78 Ma amphibole-bearing anorthosite and diorite occur in the eastern Gangdese arc. • They formed by hydrous melting of Late Cretaceous juvenile thickened lower crust. • Juvenile arc crust underwent thickening and prompt reworking during Late Cretaceous. • Volumetrically minor, 85–75 Ma, crustal melts reflect flat-slab subduction. The Gangdese arc in southern Tibet formed during subduction of the Neo-Tethyan ocean and is characterized by mantle-derived magma accretion and juvenile crustal growth. A main period of magmatism and juvenile crustal growth occurred during the Cretaceous, but little is known about the petrological component, nature, and evolution of the lower arc crust at that time. Here, we report systematic petrologic, geochemical and geochronologic data for amphibole-bearing anorthosite and diorite from the eastern Gangdese arc. The studied rocks occur within early Late Cretaceous gabbro or meta -gabbro, and consist mainly of plagioclase and amphibole with other hydrous phases, including minor muscovite, biotite and epidote. Zircon U–Pb dating gives Late Cretaceous crystallization ages of ca. 78 Ma. The rocks have varying SiO 2 (47.44–57.35 wt%), Al 2 O 3 (19.76–25.15 wt%), MgO (0.55–3.43 wt%) and FeO T (0.89–8.31 wt%) contents that can be explained as resulting from a primary melt with either plagioclase addition or amphibole accumulation. Trace element compositions show unusually high Sr/Y (59.3 to 948, average 278), but moderate (La/Yb) N (3.2 to 16.6, average 6.4). Isotopic compositions of Sr, Nd, and Hf (initial 87Sr/86Sr = 0.704186 – 0.704552, εNd(t) = +2.8 to + 4.6 and zircon εHf(t) = +10.2 to + 15.8) are comparable to the early Late Cretaceous gabbros that form the juvenile lower crust. These geochemical characteristics imply that the studied rocks were likely derived from hydrous anatexis of early Late Cretaceous juvenile lower crust. We suggest that shallow-angle subduction and dehydration of the Neo-Tethyan oceanic plate resulted in thickening and hydrous partial melting of juvenile lower crust to form water-rich anorthosite, diorite, and previously reported adakitic rocks during the Late Cretaceous. The juvenile lower crust of the Gangdese arc consisted of hydrous mafic granulites, and experienced distinct thickening and reworking during the Late Cretaceous. [ABSTRACT FROM AUTHOR]

During the Late Cretaceous, Earth's climate oscillated between warm and cool states, and global oceans changed between anoxic and oxic conditions, resulting in black/gray shales and oceanic red beds (ORBs) deposition, respectively. To understand such climate/ocean dynamics, this study investigated bulk Hg and Hg isotopes, as well as Fe3+/Fe2+ in Upper Cretaceous sediments deposited in southern Tibet and the North Atlantic. In both areas, black/gray shales show much higher Hg concentrations than ORBs, indicating enhanced Hg flux to global oceans during time of black/gray shale deposition. Black/gray shales show lower Fe3+/Fe2+ and positive Δ199Hg, suggesting a significant input of Hg into the anoxic/dysoxic ocean via atmospheric deposition. The isotope values are consistent with a volcanic source for this excess Hg. ORBs show high Fe3+/Fe2+ and negative shifts of Δ199Hg, suggesting that the dominant source of Hg into the oxic oceans was via terrestrial runoff. This study suggests that volcanism was an important driver of the climate/ocean dynamics during the Late Cretaceous. Plain Language Summary: The Late Cretaceous ocean developed widespread black/gray shales and oceanic red beds which were deposited in warm‐anoxic/dysoxic and cool‐oxic oceanic conditions, respectively. The driving force for such climate/ocean dynamics remains unclear. This study demonstrates distinct Hg concentrations and isotopic composition in black/gray shales and oceanic red beds, which suggest that volcanism was a major trigger of the climate/ocean dynamics in the Late Cretaceous. Key Points: The Late Cretaceous black/gray shales and oceanic red beds display opposing mass‐independent fractionation of Hg isotopesChanges in climate/ocean conditions had strong control on the sources of Hg in the Late Cretaceous oceanVolcanism served as an important driving force of the climate/ocean dynamics during the Late Cretaceous [ABSTRACT FROM AUTHOR]

Aeolosaurus is a late Cretaceous Titanosaur genus with two species discovered in Argentina and one in Brazil. Although the allocation of the Argentinean Aeolosaurus seems unequivocal, that is not the case for the Brazilian species Aeolosaurus maximus since several authors questioned its positioning into this genus, based on both anatomical and phylogenetic data. The revision of the diagnosis of Ae. maximus, with the proposition of a new autapomorphy, corroborates the anatomical uniqueness and our phylogenetic analysis stresses that the relation of Ae. maximus to the Argentinean Aeolosaurus is uncertain. Based upon that, we propose a new genus, Arrudatitan, to accommodate the Brazilian taxon. [ABSTRACT FROM AUTHOR]

Since their discovery in the 1920s, some asymmetric, elongated dinosaur eggs from the Upper Cretaceous of Mongolia have been interpreted as ceratopsian eggs. However, recent views support a maniraptoran affinity mainly based on macroscopic features. Technical advancements in palaeontology provide a novel approach to diagnose maniraptoran eggs, and the discovery of soft ceratopsian eggs makes the debate a timely issue worth revisiting. Here, we analysed Protoceratopsidovum eggshell from southern Mongolia with electron backscatter diffraction and the results were compared with East Asian and North American maniraptoran and ornithischian eggs. The microstructure and crystallography of Protoceratopsidovum confirms the maniraptoran hypothesis, given that it shows diagnostic features of the clade absent from ornithischian (e.g. hadrosaur) eggs. Additional characters, such as egg shape, ornamentation, egg pairing and clutch structure also support a maniraptoran affinity. Protoceratopsidovum has both elongatoolithid (oviraptorosaur egg) and prismatoolithid (troodontid egg) features, and it may bridge the morphological gap between the two established oofamilies. Considering the similarity between Protoceratopsidovum and potential dromaeosaur eggs, at least some Protoceratopsidovum may be deinonychosaur eggs. Fossil localities that yield both deinonychosaurs and Protoceratopsidovum may yield conclusive evidence for the true affinity of this ootaxon. Future discovery of the egg‐laying taxon of Protoceratopsidovum will not only improve our understanding of maniraptoran reproductive biology but also make Protoceratopsidovum a reliable indicator of the palaeobiogeography of that maniraptoran clade. [ABSTRACT FROM AUTHOR]

Nine ostracod species are described from the Late Santonian - Campanian of Wadi Al-Kharaj section, northwestern Jordan. These species provide valuable information for biostratigraphy and paleobiogeography of the southern Tethys realm. The nine species belong to the following genera: Cytherella, Bythocypris, "Togoina", Brachycythere, Cythereis, "Veenia", Ventrocythereis, and Cristaeleberis. These species confirmed that the top of the Wadi Ghudran Formation and the base of the Amman Formation span the Coniacian-Campanian boundary. Brachycythere provides valuable information on the palaebiogeography of the shallow marine ostracodes. [ABSTRACT FROM AUTHOR]

Abstract During the Late Cretaceous, Earth's climate oscillated between warm and cool states, and global oceans changed between anoxic and oxic conditions, resulting in black/gray shales and oceanic red beds (ORBs) deposition, respectively. To understand such climate/ocean dynamics, this study investigated bulk Hg and Hg isotopes, as well as Fe3+/Fe2+ in Upper Cretaceous sediments deposited in southern Tibet and the North Atlantic. In both areas, black/gray shales show much higher Hg concentrations than ORBs, indicating enhanced Hg flux to global oceans during time of black/gray shale deposition. Black/gray shales show lower Fe3+/Fe2+ and positive Δ199Hg, suggesting a significant input of Hg into the anoxic/dysoxic ocean via atmospheric deposition. The isotope values are consistent with a volcanic source for this excess Hg. ORBs show high Fe3+/Fe2+ and negative shifts of Δ199Hg, suggesting that the dominant source of Hg into the oxic oceans was via terrestrial runoff. This study suggests that volcanism was an important driver of the climate/ocean dynamics during the Late Cretaceous.

The Canterbury Basin in southeastern Zealandia was initiated during the late Albian (ca. 105 Ma) as a rift system, prior to the onset of seafloor spreading between Zealandia and eastern Gondwana at ca. 85 Ma. Basin‐fill architecture and sediment types have been determined from interpretation of 2D and 3D seismic‐reflection lines tied to five wells and compared to outcrop data from the literature. These data show that Cretaceous syn‐rift basin‐fill architecture was controlled by normal faulting, which produced basin and range topography that persisted for more that ca. 30 Myr after the cessation of faulting. Initial sedimentation was dominated by short drainage systems sourced from within the basin to produce alluvial fans along fault scarps, which inter‐fingered with axial‐flowing braided river conglomerates, coal measures and mudstone‐rich lake deposits in more central portions of the basins. Marine incursion of the basin from the east commenced during rifting and onset of Gondwana breakup, with maximum water depths achieved in the Oligocene. Post‐rifting, detrital sediments were mainly sourced locally from structural highs and augmented by pelagic sedimentation, which collectively draped and eventually buried most of the earlier‐formed horsts by the Early Eocene. The temporal persistence of basin and range topography reflected the low rates of erosion of horst blocks compared to the rates of fault displacement. The lack of substantial sediment input from outside of the rift basin was a key factor in the under‐filling of the Canterbury Basin. This research emphasises the key role played by sediment supply in rift basin filling. Despite an abundance of active faulting at initiation, some rift basins may fill slowly over tens of million years after rift cessation. [ABSTRACT FROM AUTHOR]

In order to constrain whether the Lhasa–Qiangtang collision contributed to an early crustal thickening of the central Tibetan Plateau prior to the India–Asia collision, we present zircon LA–ICP–MS U–Pb ages, whole-rock geochemistry, and zircon Hf isotopic compositions of the newly discovered rhyolitic crystal tuffs from the Chuduoqu area in the eastern Qiangtang subterrane, central Tibet. Zircon U–Pb dating suggests that the Chuduoqu rhyolitic crystal tuffs were emplaced at ca. 68 Ma. The Chuoduoqu rhyolitic crystal tuffs display high SiO2 and K2O, and low MgO, Cr, and Ni. Combined with their zircon Hf isotopic data, we suggest that they were derived from partial melting of the juvenile lower crust, and the magma underwent fractional crystallization and limited upper continental crustal assimilation during its evolution prior to eruption. They should be formed in a post-collisional environment related to lithospheric mantle delamination. The Chuduoqu rhyolitic crystal tuffs could provide important constraints on the Late Cretaceous crustal thickening of the central Tibetan Plateau caused by the Lhasa–Qiangtang collision. [ABSTRACT FROM AUTHOR]

In this study, we restudied a rarely known oospecies from China, Stromatoolithus pinglingensis. Original materials from type locality Nanxiong, Guangdong Province as well as recently recovered materials from Shanyang, Shaanxi Province and Laiyang, Shandong Province are compared in this study. After detailed study about general and micro-structure of these eggshells, we are sure that this ootaxon cannot be placed within Spheroolithidae or any other oofamilies, though new oofamily cannot be erected due to lack of complete specimen. In the meantime, we reviewed some Spheroolithidae eggs from Asia, North America, and Europe. We propose that the Mongolia oospecies Spheroolithus maiasauroides is a synonym of Stromatoolithus pinglingensis. Eggs of Maiasaura, Spheroolithus albertensis from North America and Spheroolithus europaeus from Spain should be reassigned to Stromatoolithus. The Lower Cretaceous oospecies Guegoolithus turolensis from Spain should also be considered as ootaxon with close relationship to Stromatoolithus but not Spheroolithidae. The geographic distribution of Spheroolithidae may not be so wide as former researchers thought, and the producer of Spheroolithidae is back to unknown. The oogenus Stromatoolithus is associated with hadrosaurs, and may restrict to Hadrosauridae. [ABSTRACT FROM AUTHOR]

Late Cretaceous felsic volcanism erupted as calderas in the terminal stage of the massive Cretaceous volcanism in SE China. This paper reports comprehensive geochemical and isotopic data for high-silica rhyolites from the Shiniushan and Xiaoxiong calderas in eastern Fujian–Zhejiang provinces, SE China. Zircon U-Pb dating constrains these rhyolites eruptions to 94–92 Ma and 93–89 Ma in the sites of the two calderas. All the samples possess high-silica contents with peraluminous characteristics and are enriched in light rare earth elements (LREEs), Rb, and Th-U and depleted in Ba, Nb-Ta, Sr and Eu. These samples have high whole-rock F (114–596 ppm) but low Cl (3.3–54.8 ppm) contents. Apatite minerals separated from the high-silica rhyolites are classified as fluorapatite and show F-rich (F > 3.56 wt%), Cl-poor (Cl < 0.02 wt%), low (La/Sm) N and high (Gd/Yb) N ratios, with a negative Eu anomaly. The high-silica rhyolites yield initial (87Sr/86Sr) i ratios of 0.70405 to 0.70789, negative whole-rock ε Nd (t) (−3.3 to −6.3), negative apatite ε Nd (t) (−5.2 to −6.6) and negative zircon ε Hf (t) values (−0.1 to −9.6). Our data suggest that their primary magma was derived from modified crustal sources that could contain a mixture of ancient and juvenile components, and it then evolved, was injected into a low-pressure magma chamber, and finally erupted with the release of volatiles at the magma chamber roof. We infer that SE China was mainly under a setting of lithospheric extension from the Early to early Late Cretaceous because of slab roll-back and steepening of the subducted Paleo-Pacific Plate. [Display omitted] • High-silica rhyolites erupted on Xiaoxiong and Shiniushan calderas at 94–89 Ma. • Crustal sources were modified by magmatic underplating beneath SE China. • High-silica lavas erupted at low-pressure magma chamber with F-rich and Cl-poor. • Paleo-Pacific slab roll-back induced Late Cretaceous extension and volcanism. [ABSTRACT FROM AUTHOR]

The depositional environment of the Tanjero Formation has been studied depending on foraminiferal assemblage and microfacies analysis in the Hujran section, northeast of Erbil City (Iraqi Kurdistan Region). The formation in the studied section consists of 30 m of thin bedded yellowish blue marly limestone interbedded with blue marl in the lower part, whereas the upper part consists of thin yellow limestone and yellowish blue marly limestone interbedded with gray marl, shale, and sand. The foraminifera species are extracted from fourteen samples of friable sediments in the studied section. The result shows that the planktonic and benthonic foraminifera have a high abundance and diversity. Based on the ratio of planktonic/total (planktonic + benthonic) %, the paleodepth of the friable rocks of Tanjero Formation in the Hujran section is mostly upper slope with occasional intervals back to the outer shelf. The petrographic components of 15 thin sections of carbonate rocks of the Tanjero Formation include skeletal grains which are planktonic foraminifera, benthonic foraminifera, calcispheres, echinoid spines, ostracoda, bryozoa, brachiopods, bivalves, and bioclasts. Non-skeletal grains contain only extraclasts of monocrystalline quartz. The main groundmass is composed of micrite with some microspars. Three main microfacies were recognized in the Tanjero carbonates. They are grouped into one basic type of facies association based on their environmental interpretation, which is the deep shelf and lower slope. The proposed depositional environment of the Tanjero Formation is a deep shelf and slope environment depending on field observation, foraminiferal content of friable rocks, and microfacies analysis of carbonate rocks. [ABSTRACT FROM AUTHOR]

The western North China Craton (NCC) entered a stage of craton thinning concentrated on its margin in the Cenozoic, but its Late‐Cretaceous conditions were previously deduced to be relatively quiescent. Therefore, whether the Late‐Cretaceous tectonic reactivation existed on the margin of this block is critical to understanding how the craton evolved into a thinned one. To investigate this possible margin reactivation in the Late Cretaceous, we apply zircon (U‐Th)/He thermochronology to Taibai Mountain on the southern margin of the western NCC. From an ∼3‐km‐high vertical profile with ages decreasing from 98 ± 5 Ma at the peak to 52 ± 7 Ma at the foot, the age‐elevation relationship suggests the rapid exhumation at ca. 78–71 Ma bracketed by two slow exhumation phases. This interpretation is confirmed by 1D half‐space modeling and QTQt inverse modeling, with the rapid exhumation stage having an exhumation rate of 0.1–0.6 km/Myr and a cooling rate of ∼10°C/Myr. Together with previously reported thermochronological data from the margin of the western NCC, the rapid exhumation at ca. 78–71 Ma implies a reactivated margin in the Late Cretaceous before widespread Cenozoic thinning of the craton margin. This Late‐Cretaceous reactivation likely resulted from WNW‐ESE extension expressed by thermo‐tectonic events, basin subsidence, and volcanism in East Asia. Excluding impacts from climate change, lithospheric delamination, and India subduction beneath Eurasia, we infer that the Late‐Cretaceous reactivation on the margin of the western NCC was driven by the far‐field effect of Izanagi Plate subduction beneath the Eurasian Plate during slab rollback of the subducted plate. Key Points: Rapid exhumation of Mt. Taibai at ca. 78–71 Ma is confirmed by the age‐elevation relationship, 1D half‐space modeling, and QTQt modelingSynchronous Late‐Cretaceous rapid exhumation suggests a reactivated margin of the western North China Craton before Cenozoic thinningThis reactivation was triggered by the far‐field effect of Izanagi Plate subduction beneath the Eurasian Plate [ABSTRACT FROM AUTHOR]

The Nemuro and Saroma Groups and Yusenkyo Formation occur in eastern Hokkaido and are considered to be forearc or intra‐arc basin sediments of the Paleo‐Kuril arc (PKA) deposited during the Late Cretaceous to middle Eocene. To further clarify the origin of the PKA, we examined the U–Pb ages of detrital zircons within these sandstones and acidic tuff beds; based on our results, we drew the following conclusions. (1) The PKA originated from an oceanic island arc on the oceanic Izanagi Plate around 85 Ma, to which the Nikoro Group greenstone complex was accreted between 81–80 Ma; the Lowest Unit of the Saroma Group covered the surface of the Nikoro accretional greenstone complex. (2) The PKA then first collided with NE Asia around the beginning of the deposition of the Hamanaka Formation (~70 Ma) and transitioned to a continental arc adjacent to NE Asia. This collision generated giant slump beds during deposition of the Akkeshi Formation. During deposition of the Kiritappu Formation, the entire Nemuro Peninsula was uplifted, supplying large volumes of clastic sediments. (3) Although we do not have data directly bearing on why the North American Plate was established in the edge of NE Asia, we speculate that it separated from the Eurasian continent around ~70 Ma when NE Asia first collided with the PKA. Subsequently, the PKA has behaved as part of the North American Plate. The Paleo‐Japan arc (or East Sikhote–Alin arc) and the PKA became joined via the Hidaka Belt. Around 40 Ma, during the deposition of coarse conglomerate beds of the Urahoro Group, the PKA was uplifted and bent clockwise due to a second collision with NE Asia. (4) The modern Kuril arc was established around 36 Ma (late Eocene–early Oligocene), and the Kuril backarc basin opened into the present tectonic setting in the late Oligocene–early Miocene. [ABSTRACT FROM AUTHOR]

Summary: We describe two new fossil woods from the San Carlos Formation (Upper Cretaceous), Chihuahua State, Mexico. The first wood resembles the fossil genus Metcalfeoxylon in having solitary vessels, scalariform perforation plates, vessel-ray parenchyma pits of similar size as the intervessel pits, axial parenchyma apotracheal diffuse and diffuse in aggregates, and heterocellular multiseriate rays with long, uniseriate tails. The second wood is a new fossil genus, and it is characterized by having diffuse porous wood, vessels predominantly solitary, vessel outlines oval and tending to be of two diameter classes, simple perforation plates, minute alternate intervessel pits, vessel-ray parenchyma pits similar to intervessel pits in size and shape, vasicentric tracheids, non-septate fibers, homocellular rays, and exclusively uniseriate and biseriate rays. This combination of features supports its placement in Myrtales (?Myrtaceae), in a new fossil-genus named Lazarocardenasoxylon. These two new records provide more information about the floristic composition of the Late Cretaceous flora of the San Carlos Formation and its relationship with those from the southern USA. However, a definitive picture of the floristic relationship of these Cretaceous floras of northern Mexico and southern USA remains elusive. [ABSTRACT FROM AUTHOR]

Nine shark teeth were collected at Arnager in the south-western part of the island of Bornholm (Baltic Sea, Denmark). They all come from the basal conglomerate of the Coniacian (Upper Cretaceous) Arnager Limestone Formation and belong to the genus Ptychodus Agassiz, 1834. Three different species are identified: P. altior, P. latissimus and P. mammillaris, which were hitherto unknown in Denmark. [ABSTRACT FROM AUTHOR]

T he petrogenesis and geodynamic mechanism of Late Cretaceous magmatic rocks in southern Lhasa terrane, Tibet, are still controversial. T he hornblende gabbros and quartz diorites in the west of Chabala area, Qushui county of southern Lhasa terrane were selected as the research object, and based on field geological surveys, the petrography, geochemistry and Ll\- ICP-MS zircon U-Pb geochronology were analyzed to identify the formation ages and petrogenesis of hornblende gabbros and quartz diorites, and further constrain the tectonic evolution of southern Lhasa terrane during Late Cretaceous. T he results show that the hornblende gabbros emplace at 91-87 Ma, and the quartz diorites emplace at 81 Ma. T he hornblende gabbros have low contents of SiO2 (48. 16% - 51. 05%), high contents of MgO (4. 54%- 11. 13 %), Co ((31. 2-46. 8) X 10-6 ) and Ni ((1. 79-82. 70) X 10-6 ), and ( 87 Sr/86 Sr); value is 0. 703 925- 0. 704 380, €Nd (t) value is 2. 50 - 3.96, indicating that the hornblende gab bros are generated by partial melting of a depleted mantle wedge that have been metasomatized by slab-derived fluid, and suffer from no obvious crustal contamination. T he quartz diorites are generally high Si02 ( 62.45 % - 62.90 %), AI2O3 05.94 % -16.22%), K2O+Na2O (6.36%-6.46%) and Mg# value (43. 77 - 44. 65 ), thus can be grouped into quasi aluminous I-type granite. T he quartz diorites are generated by partial melting of the lower crust and mix with a little mantle-derived magma. Both rocks show the characteristics of arc magma with enrichment of LREEs and LILEs (such as Rb, Th, U and Sr), and depletion of HREEs and HFSEs (such as Nb, Ta and Ti). Integrating regional data, the "flare-up" event in southern Lhasa terrane during the early Late Cretaceous Cl 00-80 Ma) is likely the result of the northwards subduction of an oceanic ridge of Neo-Tethys. T he ridge subduction would have resulted asthenosphere material upwelling through a slab window and decompression melting to form a basic magma, which provides heat to cause partial melting of the mantle wedge and lower crustal rocks, resulting in the magma eruption during the early Late Cretaceous of southern Lhasa terrane. [ABSTRACT FROM AUTHOR]

Granitoids and their hosted microgranitoid enclaves (MEs) can provide crucial information in understanding the evolution of granitoids and continental crustal growth. The Guyong pluton in central Tengchong Block is mainly composed of monzogranites and abundant coeval MEs (76 Ma). This study reports their petrological, geochemical, and Sr–Nd, zircon U–Pb, and Lu–Hf–O isotopic features to shed light on their petrogenesis and the evolution of the Neo‐Tethys. The Guyong MEs have low SiO2 (56.88–69.61 wt%) and high MgO (1.04–3.91 wt%) contents. They have typical igneous textures and are characterized by similar mineral assemblages, chondrite‐normalized rare earth element diagrams, and Sr–Nd and zircon Hf–O isotopic compositions (εHf(t) of −9.0 to −2.3, δ18O of 6.57–8.07) with their host monzogranites, indicating that they are cognate. The acicular apatite and fine‐grained texture and geochemical characteristics suggest that the MEs were generated in a rapid cooling and crystallization process at the margin of magma conduit. The Guyong monzogranites have high SiO2 contents (70.79–74.24 wt%) and low MgO contents (0.24–0.78 wt%). They are calc‐alkalic and weakly peraluminous and show characteristics of I‐type granites. The geochemical and isotopic compositions of the Guyong monzogranites and MEs suggest that they were produced by partial melting of the metasedimentary and meta‐igneous rocks from the Proterozoic Gaoligong metamorphic complex. The Late Cretaceous magmatism in the central Tengchong Block is correlated with the northward subduction of the Neo‐Tethys. [ABSTRACT FROM AUTHOR]

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The latest Cenomanian to Santonian sedimentary record recovered at IODP Expedition 369 Site U1513 in the Mentelle Basin (SE Indian Ocean, paleolatitude 60°S at 85 Ma) is studied to interpret the paleoceanographic evolution in the Southern Hemisphere. The planktonic foraminiferal assemblage changes, the depth ecology preferences of different species, and the surface and seafloor temperature inferred from the stable isotopic values measured on foraminiferal tests provide meaningful information to the understanding of the Late Cretaceous climate. The hothouse climate during the Turonian‐Santonian, characterized by weak latitudinal temperature gradients and high atmospheric CO2 concentrations, is followed by a progressive cooling during the Campanian. At Site U1513 the beginning of this climatic transition is nicely recorded within the Santonian, as indicated by an ∼1‰ increase in δ18O values of planktonic foraminifera suggesting a decline in surface water paleotemperatures of 4°C. The onset of cooling is mirrored by changes in the planktonic foraminiferal assemblages including extinctions among surface and deep dwellers, appearances and diversification of newly evolving taxa, and changes from predominantly epifaunal oxic to infaunal dysoxic/suboxic taxa among co‐occurring benthic foraminifera. Overall, the data presented here document an interval in the Santonian during which the rate of southern high latitude cooling increased. Both surface and bottom waters were affected, although the cooling signal is more evident in the data for surface waters. This pattern of cooling ascribes the deterioration of the Late Cretaceous climate to decreased CO2 in the atmosphere and changes in the oceanic circulation correlated with enhanced meridional circulation. Key Points: Latest Cenomanian‐Santonian integrated planktonic foraminifera and calcareous nannofossils biostratigraphy at southern high latitudes (62°S)Onset in the Santonian of the Late Cretaceous cooling revealed by foraminifera changes and stable isotopes in the Southern HemisphereThe Santonian cooling event affected surface and bottom waters and was more dramatic in the surface waters with paleotemperatures of 14°C [ABSTRACT FROM AUTHOR]

A total of 227 theropod teeth have so far been recovered from the upper Campanian Laño site (northern Iberian Peninsula). The teeth were studied for their qualitative and quantitative features. From the theropod sample found at Laño, seven morphotypes attributed to five taxa are identified: a medium to large abelisaurid (Arcovenator sp.) and four small coelurosaurians (Dromaeosauridae indet., Paraves indet., cf. Paronychodon sp. and cf. Richardoestesia sp.) Together with the ground bird Gargantuavis and a possible ornithomimosaur, the theropod fauna of Laño might be composed of two medium–large‐sized non‐avian theropods, four small‐bodied non‐avian theropods and a large terrestrial bird. This makes the Laño site the richest and most diverse latest Cretaceous theropod site in Europe. Furthermore, the Laño site and the Upper Cretaceous localities of Europe that have yielded theropod remains suggest that the medium–large‐sized theropods were abelisaurids or indeterminate theropods. The small theropods are more abundant, diverse and represented by different dromaeosaurids, Paronychodon, Richardoestesia or related forms, troodontids and, probably, by other paravians. Of the birds, enantiornithines, gargantuaviids and ornithurines are also common in the European Upper Cretaceous sites. The theropod assemblage of Laño, together with the taxa of other Upper Cretaceous sites, supports the idea that several theropod dispersal events took place during the Cretaceous. This resulted in a mixture of European endemic, Asiamerican and Gondwanan forms. This study also supports the hypothesis that the intra‐Maastrichtian faunal turnover that occurred in the Ibero‐Armorican landmass seems to have had no apparent effect on theropods. [ABSTRACT FROM AUTHOR]

An assemblage of plant fossils from the Kyzyl-Jar locality (southern Kazakhstan, Turonian) including polymorphic leaves of Ettingshausenia cuneifolia (Angiospermae), dispersed carpels, and solitary stamens, is studied. The morphology of the E. cuneifolia leaves resembles that of representatives of the Platanaceae. The dispersed carpels, Platanocarpelia kyzyljarica gen. et sp. nov. (Platanaceae), have an oval ovary with a long persistent style, and lack a hair tuft at the carpel base. Solitary stamens are morphologically similar to those of the extant genus Platanus. E. cuneifolia leaves show significant damage by various agents, mainly arthropods. The problem of classification of these plant fossils is discussed. [ABSTRACT FROM AUTHOR]

Turonian to Maastrichtian exotics-bearing deposits from the Pieniny Klippen Belt (Klape and Kysuca units) and from the Považský Inovec Mts. (Western Carpathians) were analyzed for heavy minerals and compared with similar, yet older Albian-Cenomanian deposits. The Turonian to Maastrichtian deposits are petrographically more variable in composition in the entire range, from quartz arenites to litharenites. Percentages of the main heavy minerals are similar on both stratigraphic levels, i.e., they are dominated by chrome-spinels, zircon, tourmaline, apatite, and rutile. Garnet is more common in the Turonian to Maastrichtian samples, while titanite, kyanite, monazite, hornblende, blue amphibole, pyroxenes, epidote, staurolite, and sillimanite are quite rare. Statistical factor analysis indicates dominance of ophiolites and older sediments in the source areas. One important factor is an influx of garnet, with the weakest factor being related to the influx of tourmaline and apatite, which may indicate low-grade metamorphics. Spinels were derived from harzburgites (supra-subduction peridotites). The majority of tourmalines were derived from metasediments, Fe3+-rich quartz-tourmaline rocks, calc-silicate rocks, and metapelites and granitoids. Some had complex zonation with two phases of tourmaline (schorl-dravite and bosiite), or tourmaline intergrown with quartz. These were likely derived from ophiolitic sources. Garnets are predominantly almandinic and derived from rocks that had been metamorphosed up to the amphibolite facies, or magmatic rocks. Common pyrope-almandinic garnets indicate their source from granulites and eclogites. The main change after the Albian-Cenomanian period is the more expressed presence of the continental crust segments in the source area in comparison with ophiolites. [ABSTRACT FROM AUTHOR]

The Upper Cretaceous Iharkút vertebrate locality (Bakony Mountains, Hungary) provided a diverse lizard fauna. In order to infer their food preference, jaw and tooth morphology, as well as dental macro- and microwear, were analysed. Due to preservation, only specimens of three taxa (Chromatogenys, Bicuspidon, 'Scincomorpha indet. A') were studied. Extant lizards, including omnivores, durophages, insectivores, molluscivores and a herbivore, were used as analogies for interpretation. Based on morphological and dental wear studies, Chromatogenys seems to have consumed and processed hard objects regularly with its enlarged posterior teeth. In contrast, Bicuspidon with its complex bicuspid teeth might have fed on both softer and harder food items, and according to dental wear analysis, its diet can be placed between herbivory and insectivory. The sharply pointed teeth and jaw morphology of 'Scincomorpha indet. A' are comparable to recent insectivorous taxa though tooth crown morphology is most similar to burrowing species. This investigation is considered as a pilot study providing insight into the complexity of food chains of the Late Cretaceous Iharkút terrestrial communities. Furthermore, our results clearly demonstrate that the two-dimensional dental microwear analysis works well on the small (tooth crown diameter less than 1 mm) teeth of both extinct and extant lizards. [ABSTRACT FROM AUTHOR]

Albanerpetontids are an extinct clade of salamander-like lissamphibians characterised by features such as fused frontals and sculptured skull roof bones. Here we provide a histological analysis of the fused and sculptured frontals in two Late Cretaceous species of the type genus Albanerpeton sensu lato that differ in body size: moderate-sized 'Al.' gracile and larger-sized 'Al.' nexuosum. Despite general similarities in microanatomy/histology (no sutural trace remains between left and right frontals; sculpture formed by appositional growth of bone; predominance of parallel-fibred bone; and lack of growth marks, secondary osteons, and Sharpey's fibres) and the presence of sub-ventrolateral crest canals (possible albanerpetontid synapomorphy), 'Al.' nexuosum differs from 'Al.' gracile in exhibiting: a distinct three-layered diploë structure; bone remodelling; a higher degree of vascularisation; and more numerous osteocytic lacunae. We suggest that (1) histological differences between 'Al.' gracile and 'Al.' nexuosum are related to differences in absolute body sizes and relative development of sculpture and robustness of frontals and (2) the sub-ventrolateral crest canals in albanerpetontids are homologous to the canalis arteriae orbitonasalis in modern anurans. Two features (internal vascularisation and lack of Sharpey's fibres) support a recent suggestion that albanerpetontids may have relied entirely on cutaneous respiration. [ABSTRACT FROM AUTHOR]

This study deals with the biostratigraphy of Shiranish Formation (Late Cretaceous), depending on the Ammonite and associated Foraminifera in four outcrop sections, three of which are located in Al-Sulaimaniya governorate (Dokan, Esewa and Kanny dirka sections) and one in Erbil governorate, northern Iraq (Hijran section). Fourteen species of Ammonite belonging to fourteen genera were determined, which are: Dsemoceratidae, Gaudryceras, Gunnarites, Hoplitoplacenticeras, Kitchinites, Kossmaticeratinae, Neancyloceras, Neokossmaticeras, Nostoceras, Paratexanites, Partschiceras, Phylloceras, Pseudophyllites and Yubariceras. Also, thirty- five species of Foraminifera belonging to thirteen genera were determined, which are: Cibicides, Cymopolia, Eggellina, Elphidium, Globigerinelloides, Globotruncana, Hedbergella, Heterohelix, Marginulina, Miliolid, Neobulimmina, Nodosaria and Textularia. Seven range zones were determined, three of which are of Ammonite, which are: Desmophyllites larteti (Seunes, 1892), Nostoceras (Nostoceras) hyatti and Pseudophyllites teres (Van Hoepen, 1920), whereas the others are of Foraminifera species, which are: Glt. gagnebini Tilev, Glt. tricarinata lapparenti Brotzen, Glt. tricarinata tricarinata (Querean) and Glt. Stuartiformis Dalbiez. According to these findings, the age of Shiranish Formation was determined as the Late Campanian- Maastrichtian. [ABSTRACT FROM AUTHOR]

The "Cretaceous oceanic red beds (CORBs)" associated with "oceanic oxic events" have become a hot topic for geologists from around the world. In southern Tibet, the CORBs are widely distributed in the Upper Cretaceous of the northern Tethys Himalayas, but they have never been reported from the southern Tethyan Himalaya (Tibet, China). A mixed Upper Cretaceous carbonate‐shale succession is well exposed in the Gyabukeqing section of Guru town, Yadong County, southern Tibet, which tectonically belongs to the southern Tethyan Himalaya. These sedimentary strata constitute the transition from the Gangbacunkou Formation shale towards the Zongshan Formation limestone through the Jiubao Formation alternations of marl and shale. The Gangbacunkou Formation is characterized by grey‐greenish shales occasionally interspersed with laminated marls, followed by the Jiubao Formation composed of marls with interbeds of shales, which is overlain by the limestones of the Zongshan Formation. A 5‐m‐thick purplish marl bed was found from the lower Jiubao Formation in the Gyabukeqing section, and these reddish marls are assignable to shallow marine red beds. Detailed foraminifer biostratigraphy established five planktic foraminifer zones: Dicarinella covcavata, D. asymetrica, Globotruncanita elevata, G. ventricosa, and Radotruncana calcarata throughout the entire Upper Cretaceous succession in the Gyabukeqing section. The reddish marl beds are constrained as middle Campanian in age as they are calibrated to the middle part of the foraminifer Radotruncana calcarata Zone. As a comparison, the typical CORBs of pelagic–hemipelagic settings are also documented from the Upper Cretaceous of the northern Tethys Himalayas in southern Tibet. A total of 10 microfacies were recognized from the entire sequence of the Upper Cretaceous outer shelf‐slope settings in the Yadong area, southern Tibet. The Yadong red marl beds represent the sedimentation of the foraminiferal biomicrite/foraminiferal wackestone and mudstone/mudrock microfacies, pointing to a shallow marine continental shelf margin setting. Global biostratigraphic correlations indicate that the Yadong red marl beds are coeval with the typical CORBs of the Gyangze and Kangmar documented from the northern Tethys Himalayas in this study or reported previously from the same region as well as elsewhere in the world. The Yadong red beds also are comparable in lithology and biostratigraphy with the shallow marine red beds documented from Europe, and they all may represent the contemporaneous deposition of the CORBs in shallow shelf. These shallow marine CORBs share similar depositional mechanisms: undergoing a phase of iron and manganese enrichment in seawater due to injection of deep sea anoxic water to shallow shelf, followed by oxidization in shallow settings or being oxidized during diagenetic process or a response to the oxygenation of coeval CORBs in deep seas. [ABSTRACT FROM AUTHOR]

We describe the first maxillae and additional new specimens of Reigitherium bunodontum, a small meridiolestidan from the Late Cretaceous La Colonia Formation, Patagonia, Argentina. The new material supports a dental formula of I?, C1, P4, M3, resolves postcanine positional uncertainty and corrects previous interpretations. Our phylogeny recovers Reigitherium as a meridiolestidan allied to other bunodont Mesungulatoidea, as the sister group of the Paleocene Peligrotherium. Posterior premolars/molars of Reigitherium, and to a smaller degree Peligrotherium, are dominated by an incomplete transverse ridge running between the protoconid-metaconid in the lowers and the paracone-stylocone in the uppers, semi-symmetrical basins developing mesially and distally from these central ridges. The trigonid-derived single transverse crest results from a mesial shift of the robust metaconid, an enhancement of the basin crest stretching from the protoconid/metaconid, and a shallower trigonid basin. The mesungulatoid condition, with its complete absence of talonid, contrasts sharply with that of therians with lophs, or transverse ridges, which involved at least one talonid-derived loph resulting in two transverse crests per tooth. Mesungulatoid meridiolestidans achieved complex tooth-on-tooth occlusion with a predicted increase in herbivory/omnivory, departing from the traditional sharp-cusp insectivores plesiomorphic for meridiolestidans and Mesozoic mammals in general. Reigitherium's dramatic remodeling of the primitive meridiolestidan molar morphology, extensive continuous occlusal surface, accessory cuspules, and highly textured crenulated enamel illustrates one of most distinctive adaptations to herbivory among Mesozoic mammals. [ABSTRACT FROM AUTHOR]

A rare early Campanian (Aquilan) assemblage consisting of disarticulated anuran bones is described from the Aguja Formation of West Texas, USA. Many specimens within the assemblage pertain to taxonomically informative elements (maxillae, urostyles, and ilia). Morphological variety among specimens pertaining to each suggests high local species richness comparable with that seen elsewhere among frogs from similarly well-sampled localities of the Late Cretaceous Western Interior. Comparison between environmentally and temporally analogous microvertebrate assemblages in southern Utah, USA, reveals that anurans in both areas exhibit morphological similarities consistent with regionally allied 'southern' faunas. Among their differences, one character (dorsal protuberance of the ilium) consistently exhibited among some ilial morphotypes from Utah is conspicuously absent among those of West Texas. Two ostensibly exclusive ilial morphs in West Texas add additional support to the presence of taxonomically segregated, sub-regional populations of anurans in southern Laramidia during early to middle Campanian time. [ABSTRACT FROM AUTHOR]

Abstract Paleosols in an outcrop of fluvial–lacustrine red beds have been recognized in the Upper Cretaceous Yaojia Formation in southern Songliao Basin, Songyuan City, Jilin Province, NE China. They are recognized in the field by pedogenic features, including root traces and burrows, soil horizons and soil structures. Root traces are remnants of small herbaceous plants, elongating and branching downwards in the red paleosols. They are filled by calcite, analcime, and clay minerals in spaces created by the decay of the plant roots. Burrows are found near the root traces with backfilled cells made by soil-dwelling insects. Soil horizons include calcic horizons (Bk horizon) with continuous calcareous layers, argillic horizons (Bt horizon) with clay films and dark brown to black iron-manganese cutans, vertic horizons (Bw horizon) with slickensided claystone, and deformed soil structure and gleyed horizons (Bg horizon) with mottles and reticulate mottles. Soil structures of the paleosols include pseudo-anticlinal structures, subangular blocky structures, and angular blocky structures. The micro-pedogenesis characteristics are also observed, including micrite pedogenic minerals and clay skins. Based on the pedogenic features above, paleosols types including Aridisol, Alfisol, and Vertisol are interpreted in the red beds of the Yaojia Formation. Forming in the Late Cretaceous, the paleosols can provide more details about the seasonal climate conditions and terrestrial sedimentary system in lacustrine basin.

Abstract Background Exceptional preservation of endogenous organics such as collagens and blood vessels has been frequently reported in Mesozoic dinosaur fossils. The persistence of these soft tissues in Mesozoic fossil bones has been challenged because of the susceptibility of proteins to degradation and because bone porosity allows microorganisms to colonize the inner microenvironments through geological time. Although protein lability has been studied extensively, the genomic diversity of microbiomes in dinosaur fossil bones and their potential roles in bone taphonomy remain underexplored. Genome-resolved metagenomics was performed, therefore, on the microbiomes recovered from a Late Cretaceous Centrosaurus bone and its encompassing mudstone in order to provide insight into the genomic potential for microbial alteration of fossil bone. Results Co-assembly and binning of metagenomic reads resulted in a total of 46 high-quality metagenome-assembled genomes (MAGs) affiliated to six bacterial phyla (Actinobacteria, Proteobacteria, Nitrospira, Acidobacteria, Gemmatimonadetes and Chloroflexi) and 1 archaeal phylum (Thaumarchaeota). The majority of the MAGs represented uncultivated, novel microbial lineages from class to species levels based on phylogenetics, phylogenomics and average amino acid identity. Several MAGs from the classes Nitriliruptoria, Deltaproteobacteria and Betaproteobacteria were highly enriched in the bone relative to the adjacent mudstone. Annotation of the MAGs revealed that the distinct putative metabolic functions of different taxonomic groups were linked to carbon, nitrogen, sulfur and iron metabolism. Metaproteomics revealed gene expression from many of the MAGs, but no endogenous collagen peptides were identified in the bone that could have been derived from the dinosaur. Estimated in situ replication rates among the bacterial MAGs suggested that most of the microbial populations in the bone might have been actively growing but at a slow rate. Conclusions Our results indicate that excavated dinosaur bones are habitats for microorganisms including novel microbial lineages. The distinctive microhabitats and geochemistry of fossil bone interiors compared to that of the external sediment enrich a microbial biomass comprised of various novel taxa that harbor multiple gene sets related to interconnected biogeochemical processes. Therefore, the presence of these microbiomes in Mesozoic dinosaur fossils urges extra caution to be taken in the science of paleontology when hunting for endogenous biomolecules preserved from deep time.

Abstract This study investigates the process of formation of ooidal ironstones in the Upper Cretaceous-Paleogene succession in western Siberia. The formation of such carbonate-based ironstones is a continuing problem in sedimentary geology, and in this study, we use a variety of data and proxies assembled from core samples to develop a model to explain how the ooidal ironstones formed. Research on pyrite framboids and geochemical redox proxies reveals three intervals of oceanic hypoxia during the deposition of marine ooidal ironstones in the Late Cretaceous to the Early Paleogene Bakchar ironstone deposit in western Siberia; the absence of pyrite indicates oxic conditions for the remaining sequence. While goethite formed in oxic depositional condition, chamosite, pyrite and siderite represented hypoxic seawater. Euhedral pyrite crystals form through a series of transition originating from massive aggregate followed by normal and polygonal framboid. Sediments associated with goethite-chamosite ironstones, encompassing hypoxic intervals exhibit positive cerium, negative europium, and negative yttrium anomalies. Mercury anomalies, associated with the initial stages of hypoxia, correlate with global volcanic events. Redox sensitive proxies and ore mineral assemblages of deposits reflect hydrothermal activation. Rifting and global volcanism possibly induced hydrothermal convection in the sedimentary cover of western Siberia, and released iron-rich fluid and methane in coastal and shallow marine environments. This investigation, therefore, reveals a potential geological connection between Large Igneous Provinces (LIPs), marine hypoxia, rifting and the formation of ooidal ironstones in ancient West Siberian Sea.

The Late Cretaceous theropod fauna of South America is composed of Abelisauridae, Noasauridae, Spinosauridae, Carcharodontosauridae, Megaraptora, and Coelurosauria. These groups include mostly small (Noasauridae and Coelurosauria) and medium- to large-sized taxa (Carcharodontosauridae, Abelisauridae, and Megaraptora). Some of these lineages are predominantly Gondwanic (Abelisauridae, Noasauridae, Carcharodontosauridae, Megaraptora) and poorly represented in Laurasian landmasses. Particularly, several theropods have been reported from Patagonia, known either due to distinct anatomical features or due to their high degree of preservation, such as Carnotaurus, Skorpiovenator, Giganotosaurus, Megaraptor, Alvarezsaurus, and Unenlagia. here we describe a new incomplete tibia (MAU-PV-CM-653) from the Sierra Barrosa Formation (middle Coniacian, Upper Cretaceous), Patagonia, Argentina. MAU-PV-CM-653 shows an anteroposteriorly reduced cnemial crest that is strongly curved laterally. Finally, the tibia lacks a proximal extension of the fibular crest. These traits are reminiscent of tetanuran morphology and, together with the stratigraphic provenance of MAU-PV-CM-653, they allow us to assign it to an allosauroid theropod, thus improving the Allosauroidea global record for the middle Late Cretaceous.

The evolution of the Alpine Tethys margins during the beginning of the African-Eurasian convergence was little studied compared to their evolution during the post-Pangea rifting and oceanic expansion, i.e., from the Early Jurassic to the early Late Cretaceous. The present work firstly aims to make up for this shortcoming in the case of the distal European margin of the Alpine Tethys, namely the Briançonnais domain of the Western Alps. We show that this margin was affected by strong post-rifting extension mainly in Late Cretaceous-Paleocene times and propose to make it the type of the (rare) “Late Extension Passive Margins”. Remarkably, this extension shortly preceded Lutetian times, when Briançonnais margin encroached the SE-dipping subduction zone under the Adria microplate. Secondly, we assess the post-rifting evolution of the north-Tethyan paleomargin in the Maghrebides transects, i.e., south-west of the Briançonnais transect along the same European-Iberian paleomargin. For this purpose, we consider the Triassic-Eocene series of the “Dorsale Calcaire” in the Alkapeca Blocks located along southeastern Iberia until the Eocene then transported onto the North African margin. Examination of the literature shows that the Tethyan margin of the Alboran block was strongly affected by normal faulting as early as Late Jurassic-Early Cretaceous times whereas post-rifting extension of the Kabylian blocks mainly occurred in the Late Cretaceous-Paleocene like in the Briançonnais. We propose that post-rifting extension of the Alboran block southern margin resulted from the sinistral movement of Africa relative to Iberia while the later extension of the Kabylian blocks can be related to the further convergence kinematics. Subduction of the Ligurian-Maghrebian slab under the North African margin would have occurred at that time in the southward continuation of the Alpine subduction. The overriding Adria and North African margins did not experience significant compression at that time. During the Eocene, a subduction polarity reversal occurred, which was associated with the relocation of the subduction zone along the Alkapeca block. This was the beginning of the Apenninic subduction, which triggered the back-arc opening of the Mediterranean basins.

Microstructural features control the petrophysical properties of rocks. Of these, pore size is particularly sensitive when non-wetting fluids saturate the reservoir. The pore networks and physical properties (helium, water and mercury saturation porosity, bulk density, nitrogen permeability, P-wave velocity and thermal conductivity) of different rock types from a productive Upper Cretaceous (Coniacian) reservoir in the tunisian offshore are measured on hydrocarbon-washed samples. The facies sampled of Douleb Member are wackestone, packstone and grainstone textures as well as dolostone, dolomitized packstone and anhydrite textures. Based mainly on the results obtained by mercury injection, the porous facies of the Coniacian Douleb Member are characterized by a complex pore system with a large morphological and pore size variability in the rock. Porosity values range from 0.3 to 23.6%, bulk densities vary from 2.05 to 2.92 g.cm−3. The permeability is variable from 3760 mD to values below 0.01 mD (measurement limit of the device). P-wave propagation velocity values range from 2060 to 6084 m.s−1 and thermal conductivity varies from 1.43 to 3.77 W.m−1.K−1. The oil-impregnated facies with the best petrophysical characteristics are mainly the rudist-rich limestones and dolomites of the first unit (U1) of the Douleb Member. The well-sorted grainstones with small rudist debris and peloids have the best reservoir qualities. Porosity is the first order characteristic that controls petrophysical properties. The variability of permeability values around this first-order relationship is attributed to variations in the size of the pore access thresholds and connectivity. The variability in velocities is due to the shape of the voids, while the variability in thermal conductivity measurements is due to the nature of the contacts between the grains.

The first skull of Solemys (Testudines: Helochlydridae) is reported from the Late Cretaceous (Rognacian) Bastide Neuve locality, Fox Amphoux, Var, France. It is assigned to Solemys gaudryi (Matheron, 1869) on the basis of associated shell elements. Our study provides new insights regarding the skull morphology of the family Helochelydridae and suggests that Helochelydra from England and Naomichelys from North America appear to be closer to each other than to Solemys.

Uplift of the Gangdese Mountains is important to the evolution of Asian monsoons and the formation of Tibetan Plateau, but its paleoaltitude before the India-Asia collision (Late Cretaceous) is less constrained so far. In this study, we investigate whether the geological records, which are indicators of soil dryness, discovered in East Asia can provide such a constraint. Through climate modeling using the Community Earth System Model version 1.2.2, it is found that the extent of dry land in East Asia is sensitive to the altitude of the Gangdese Mountains. It expands eastwards and southwards with the rise of the mountain range. Comparison of the model results with all the available geological records in this region suggests that the Gangdese Mountains had attained a height of ∼2 km in the Late Cretaceous.

The nitrogen isotopes of the organic matter preserved in fossil fish otoliths (ear stones) are a promising tool for reconstructing past environmental changes. We analyzed the 15 N/ 14 N ratio (δ 15 N) of fossil otolith-bound organic matter in Late Cretaceous fish otoliths (of Eutawichthys maastrichtiensis , Eutawichthys zideki and Pterothrissus sp.) from three deposits along the US east coast, with two of Campanian (83.6 to 77.9 Ma) and one Maastrichtian (72.1 to 66 Ma) age. δ 15 N and N content were insensitive to cleaning protocol and the preservation state of otolith morphological features, and N content differences among taxa were consistent across deposits, pointing to a fossil-native origin for the organic matter. All three species showed an increase in otolith-bound organic matter δ 15 N of ~4‰ from Campanian to Maastrichtian. As to its cause, the similar change in distinct genera argues against changing trophic level, and modern field data argue against the different locations of the sedimentary deposits. Rather, the lower δ 15 N in the Campanian is best interpreted as an environmental signal at the regional scale or greater, and it may be a consequence of the warmer global climate. A similar decrease has been observed in foraminifera-bound δ 15 N during warm periods of the Cenozoic, reflecting decreased water column denitrification and thus contraction of the ocean's oxygen deficient zones (ODZs) under warm conditions. The same δ 15 N-climate correlation in Cretaceous otoliths raises the prospect of an ODZ-to-climate relationship that has been consistent over the last ~80 My, applying before and after the end-Cretaceous mass extinction and spanning changes in continental configuration., Competing Interests: Competing interests statement:The authors declare no competing interest.